1. Field of the Invention
Embodiments of the present invention relate to degassing methods and systems and, in particular, to methods and systems for degassing a fluid disposed in a standard syringe and for inserting a degassed fluid into a negative pressure device, such as, for example, a pump or other reservoir.
2. Description of Related Art
The use of implantable, fluid-delivering devices in the treatment of various medical conditions has necessitated requisite procedures for filling the devices with an appropriate fluid and removing “stale” fluid from the devices when necessary. Although the devices themselves, such as, for example, pumps and other reservoirs, could be surgically removed from a patient every time the addition or removal of fluid from the device is required, such an invasive surgical procedure performed multiple times would prove traumatic and debilitating to the patient. Furthermore, these types of procedures are time-consuming and expensive.
Implantable pumps and other fluid-containing reservoirs that are implanted into the human body typically operate as either a positive pressure device or a negative pressure device. Negative pressure devices have the advantage of precluding the fluid contained in the device from leaking into the body in the event the integrity of the seals of the device are compromised. Because the pressure in the pump or reservoir under which the fluid resides is negative with respect to the body, fluid would normally flow into the pump or reservoir rather than outward from the device and into the body should a break in the seals occur. Thus, a negative pressure device provides an element of safety for the patient, preventing a large, possibly toxic exposure to the fluid in the device if the seals of the device become compromised.
Filling an implanted, negative pressure device has typically been a two-step procedure. First, the fluid with which the device is to be filled is degassed. Without proper degassing, gasses that have been dissolved in the fluid could resurface as bubbles in the fluid when the fluid reaches the body, a situation that could be dangerous for the patient. Second, after degassing, the degassed fluid is inserted into the patient. This is typically done through the skin using a needle that interfaces with a port on the device.
The tools that have been available for the degas and fill procedure have been inadequate for efficiently accomplishing the procedure. For example, generally, the implant fluid is drawn into a syringe and degassed by pulling a vacuum in the syringe; however, no tool currently exists that that locks the plunger of the syringe in place once the plunger has been drawn back to create the vacuum. Thus, rather than being able to use standard, off-the-shelf syringes, prior art solutions have had to custom-modify parts of the syringe and use other external parts to lock the plunger of the syringe in place once a vacuum has been pulled. This type of solution is time-consuming, expensive and inefficient.
Also, both positive and negative pressure implant devices present challenges to the fill (or refill) procedure. In a positive pressure device, the fluid in the syringe must be at a greater pressure than the pressure existing in the device. Accordingly, the syringe used must be able to accommodate a pressure-generating apparatus to build up a presser in the barrel of the syringe.
In a negative pressure device, the fluid in the syringe will generally flow from the syringe to the device, since the pressure in the syringe is normally greater than the pressure in the device. However, under certain conditions, the pressure in the syringe may not be sufficiently greater than the pressure in the device to force the fluid to flow from the syringe to the device. In this situation, some type of mechanism must be used to generate enough pressure against the fluid in the syringe to cause the fluid to flow from the syringe into the device.